The church is located within the complex that houses the offices of the ASL Bari and the latter manages the underground site. The monumental entrance consists of an ogival Gothic arch, which opens to the first part of the access stairway to the cave.The entrance façade is surmounted by a small bell gable dominated by a bell dated 1682 and called, as in the oration dedicated to San Michele reported in bas-relief around it, "Miracle Bell". The bell tower previously stood in the rear part of the structure, later when the above facade was built it was moved to the front.
To the left of the small entrance facade is a fluted column surmounted by a metal cross. Its construction, which in an unlikely way, is attributed to the will of Gregory the Great's parents by the hand of General Tulliano XI, leader of Sipontine weapons (end of the 6th century), the date of construction is not really known.